Instruments used in radiocarbon dating
Measuring the intensity of the luminescence can determine how much time has passed since the last time the object was heated.
The light is proportional to the amount of radiation absorbed since the material was last heated.
Alternately, primary ages can be calculated if the rock was formed at the surface and cooled quickly.
Under these conditions the calculated fission-track ages of two minerals with widely different annealing temperatures would be identical.
Thermoluminescence dating is generally not very accurate.
The accuracy of thermoluminescence dating is only about 15% for a single sample and 7 to 10% for a suite of samples in a single context.
Immersing the sample in an etching solution of strong acid or base enlarges the fission tracks into tube-shaped holes large enough to be seen under a high-powered microscope.
Later heating releases the trapped electrons, producing light whose intensity is proportional to the amount of radiation absorbed.The fission tracks produced by this process are recorded by a thin plastic film placed against the surface of the sample.The uranium content of the material can then be calculated so long as the neutron dose is known.Fortunately, the uranium content of precisely the spot under scrutiny can be obtained by a similar process when working with a polished crystal surface.The sample is bombarded with slow (thermal) neutrons in a nuclear reactor, resulting in induced fission of uranium-235 (as opposed to spontaneous fission of uranium-238).